Rare-earth and transition metal doped III-nitride semiconductor thin films are attracting increasing attention as phosphor materials for use in optical displays, light-emitting diodes (LEDs) and other optical devices. Recent progress toward nitride-based light-emitting diodes and electroluminescent devices (ELDs) has been made using crystalline and amorphous GaN and AlN doped with a variety of rare-earth elements. The amorphous III-nitride semiconductors have an advantage over their crystalline counterparts because the amorphous materials can be grown at room temperature with little strain arising due to lattice mismatch. Amorphous III-nitride semiconductors may also be more suitable for waveguides and cylindrical and spherical laser cavities because of their lack of grain boundaries.
Laser diodes made from aluminum nitride (AlN) are a high-value goal for the optics industry, to be used in much the same way as gallium nitride (GaN) LEDs. Rare-earth doped glasses and insulating crystals have been extensively studied and developed for laser applications. AlN has not been given its due attention in the past, however, as a gain medium or laser material when doped with rare-earth elements and/or transition metals. While many kinds of laser cavities have been invented since the birth of the first laser in 1950s, different techniques have been attempted in the past to produce lasers with high-efficiency and low-input power. The use of lasers in biomedical applications has likewise grown. Nonetheless, a significant need still exists for less expensive, more versatile and more efficient different laser cavities. The present invention addresses these needs.